Recently, the use of non-contact IC cards has become widespread in the fields of electronic money, an electronic tickets or the like. A near-field wireless communication method and a non-contact communication protocol such as Type-A (Type A, registered trademark), Type-B, or Felica, (registered trademark) have been defined International Standards such as ISO/IEC 14443 or ISO/IEC 18092. According to the ISO/IEC 18092, NFCIP-1 (Near-Field Communication Interface and Protocol) is defined while including Felica and Type-A of ISO/IEC 14443. According to ISO/IEC 21481 (NFCIP-2), ISO15693 (non-contact vicinity IC card) and Type-B of ISO/IEC 14443 are defined in addition to NFCIP-1.
It is necessary to determine which of a plurality of communication methods should be applied for sending a frame, such that an IC card or a reader-writer corresponding to a plurality of communication methods decodes data in the communication frame.
For example, Patent Document 1 (JP 2002-342725A) discloses a configuration which measures a pulse width of a binary signal, compares the pulse width with a pulse width defined by each communication method, and selects an identical pulse width, so as to determine a communication method. For example, Patent Document 2 (JP 2010-183423A) discloses a configuration of pattern matching which samples a binary signal with a predetermined clock for a predetermined time, compares the data pattern of the sampling result with a previously held data pattern of each communication method, and selects an identical data pattern.
However, because an analogue circuit is generally used for a demodulator, a binary signal as a demodulation result includes pulse variations due to code interference, distortion, or the like by the analogue circuit. For this reason, it becomes difficult to determine a communication method based on the measurement of the pulse width or the pattern matching, resulting in a communication method determination error.